hidesBottomBarWhenPushed = NO not working?

Question

I have a UITabBar in my app, which I\'m hiding on the first UIViewController in the first tab by putting this line in the AppDelegate

Answer 1

This one works for me. Thanks to a hint in some other thread here I found a solution to hide the tab bar for one view cotroller only and to re-establish it for any view controller that is called from within.

Doing so, I can keep up the regular chain of navigation controlers.

This is what I finally got:

#define kTabBarHeight               49 // This may be different on retina screens. Frankly, I have not yet tried.

- (void) hideTabBar:(BOOL)hide {

    // fetch the app delegate
    AppDelegate         *delegate   = [[UIApplication sharedApplication] delegate];

    // get the device coordinates
    CGRect              bounds      = [UIScreen mainScreen].bounds;
    float               width;
    float               height;

    // Apparently the tab bar controller's view works with device coordinates  
    // and not with normal view/sub view coordinates
    // Therefore the following statement works for all orientations. 
    width                   = bounds.size.width;
    height                  = bounds.size.height;

    if (hide) {

        // The tab bar should be hidden too. 
        // Otherwise it may flickr up a moment upon rotation or 
        // upon return from detail view controllers. 
        [self.tabBarController.tabBar setHidden:YES];

        // Hiding alone is not sufficient. Hiding alone would leave us with an unusable black
        // bar on the bottom of the size of the tab bar. 
        // We need to enlarge the tab bar controller's view by the height of the tab bar. 
        // Doing so the tab bar, although hidden, appears just beneath the screen. 
        // As the tab bar controller's view works in device coordinations, we need to enlarge 
        // it by the tab bar height in the appropriate direction (height in portrait and width in landscape)
        // and in reverse/upside down orientation we need to shift the area's origin beyond zero. 
        switch (delegate.tabBarController.interfaceOrientation) {
            case UIInterfaceOrientationPortrait:
                // Easy going. Just add the space on the bottom.
                [self.tabBarController.view setFrame:CGRectMake(0,0,width,height+kTabBarHeight)];
                break;

            case UIInterfaceOrientationPortraitUpsideDown:
                // The bottom is now up! Add the appropriate space and shift the rect's origin to y = -49
                [self.tabBarController.view setFrame:CGRectMake(0,-kTabBarHeight,width,height+kTabBarHeight)];
                break;

            case UIInterfaceOrientationLandscapeLeft:
                // Same as Portrait but add the space to the with but the height
                [self.tabBarController.view setFrame:CGRectMake(0,0,width+kTabBarHeight,height)];
                break;

            case UIInterfaceOrientationLandscapeRight:
                // Similar to Upside Down: Add the space and shift the rect. Just use x and with this time
                [self.tabBarController.view setFrame:CGRectMake(0-kTabBarHeight,0,width+kTabBarHeight,height)];
                break;

            default:
                break;
        }
    } else {
        // reset everything to its original state. 
        [self.tabBarController.view setFrame:CGRectMake(0,0,width,height)];
        [self.tabBarController.tabBar setHidden:NO];
    }

    return; 
}


- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation{

    // It is important to call this method at all and to call it here and not in willRotateToInterfaceOrientation
    // Otherwise the tab bar will re-appear. 
    [self hideTabBar:YES];

    // You may want to re-arrange any other views according to the new orientation
    // You could, of course, utilize willRotateToInterfaceOrientation instead for your subViews. 
}

- (void)viewWillAppear: (BOOL)animated { 

    // In my app I want to hide the status bar and navigation bar too. 
    // You may not want to do that. If so then skip the next two lines. 
    self.navigationController.navigationBar.barStyle = UIBarStyleBlackTranslucent;
    [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationSlide];

    [self hideTabBar: YES];

    // You may want to re-arrange your subviews here. 
    // Orientation may have changed while detail view controllers were visible. 
    // This method is called upon return from pushed and pulled view controllers.   

    return;
}

- (void)viewWillDisappear: (BOOL)animated {     

    // This method is called while this view controller is pulled
    // or when a sub view controller is pushed and becomes visible
    // Therefore the original settings for the tab bar, navigation bar and status bar need to be re-instated

    [self hideTabBar:NO];

    // If you did not change the appearance of the navigation and status bar in viewWillAppear,
    // then you can skip the next two statements too. 
    self.navigationController.navigationBar.barStyle = UIBarStyleBlack;
    [[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationSlide];

    return;
}

The in-line comments should explain the reasoning for each statement. Though, there may be smarter ways of coding it.

There is one side effect in conjunction with hiding the status bar and navigation bar too, which I do not want to hide from you guys. 1. When returning from this navigation controller to the calling navigation controller then the status bar and navigation bar on the calling controller overlap until the device is rotated once or until the related tab has been choosen again after another tab came to front. 2. When the calling view controller is a table view and when the device is in landscape mode when returning to the table, then the table is displayed in the appropriate orientation for landscape but it is layed out as if it were portrait. The upper left corner is fine but some table cells plus tab bar are hidden beneath the screen. On the right hand side there is some free space. This, too, is fixed by rotating the device again.

I will keep you updated once I found solutions for these minor but nasty bugs.

Answer 2

Use

secondViewController.hidesBottomBarWhenPushed = NO;

When insert some operations

firstViewController.hidesBottomBarWhenPushed = YES;

Answer 3

This is what the documentation for hidesBottomBarWhenPushed says (emphasis added):

If YES, the bottom bar remains hidden until the view controller is popped from the stack.

So it looks like the behavior you're seeing is just what the documentation says will happen. You start by pushing a view controller onto the stack which has hidesBottomBarWhenPushed = YES. At that point, pushing other view controllers onto the stack won't change the hiddenness of the bottom bar. As long as that first view controller is on the stack, the bottom bar will remain hidden.

So I think you'll have to come up with a different way of accomplishing your UI goal. One option would be to present the first view controller as a modal view controller over the tab bar controller's view. Then, when you want to go to the second view controller just dismiss the first one and voila. The only visual difference will be the transition animation.

There are surely other options too, but that just came first to my mind.

Good luck!